Appending with bpy.data.libraries.load and drivers
The following code does the trick:

import bpy

# prepare files list for bpy.ops.wm.append(..)
files = []
with bpy.data.libraries.load("path/to/test.blend") as (data_from, data_to):
    for name in data_from.objects:
        files.append({'name': name})

bpy.ops.wm.append(directory="path/to/test.blend"+"/Object/", files=files)